Why didn't they keep right on going with G, H, I, J, K, L, M, N, O, P?

为什么他们不接着写下去呢,按照字母表

耶鲁公开课 - 聆听音乐课程节选

But you can look at manuscripts of the early eleventh century and see people singing Ps and Ls and Os and Ms and things like that.

但是大家可以看看,十一世纪初的手稿,可以看到那时有人在唱P,以及L,O和M之类的

耶鲁公开课 - 聆听音乐课程节选

So it's OK to not specify. I want to point out, pz whether you're in the p x, the p y, or the p z, unless a question specifically m asks you to specify the m sub l, which occasionally will happen, but if it doesn't happen you just write it like this.

我想指出的是，无论你在px，py或，除非一个问题特别地,让你指出l下面的，这种情况有时会发生，这样就可以了,但是如果它不做要求你们写成。

麻省理工公开课 - 化学原理课程节选